I use some ancient ergopower levers (8 speed) on our tandem. The left lever works fine with Shimano front cantilever due to short cable run. I was only happy with Strange cantilever for the rear after lots of judicious effort at removing cable slack.
When we changed tandem, I switched to TRP Spyre for the rear so switched to dealing with different set of problems.
I am quite heavy and my touring bicycle came with the Spyres. I have Spyres, Spyke and HY/RD disk calipers sitting in my tool box. They are made light and flimsy. I have the Paul Klampers and wished I had had them from the start. You can order them with long, short or Campi caliper length arms. They are expensive and worth every penny that I paid for them. I also use Yokozuna compressionless brake cable housing. It is the best compressionless housing. The Paul Klampers have no play in them and they are not flimsy. Although I would only by Paul products if you like to stop.